ListView的另一种可读性更强的ViewHolder模式写法

常见的写法是这样的：

@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder viewHolder;

if( convertView == null ) {
convertView = getLayoutInflater().inflate( R.layout.line, null );
ImageView imageView = (ImageView) convertView.findViewById( R.id.imageView );
TextView textView = (TextView) convertView.findViewById( R.id.textView );
viewHolder = new ViewHolder();
viewHolder.imageView = imageView;
viewHolder.textView = textView;
convertView.setTag( viewHolder );
} else {
viewHolder = (ViewHolder) convertView.getTag();
}

viewHolder.imageView.setImageResource( R.drawable.ic_launcher );
viewHolder.textView.setText( arr[ position ] + "");
return convertView;
}

但是可读性不好，convertView怎么会当成getView的返回值呢？所以以下是一种更好的写法：

@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder viewHolder;
if( convertView == null ) {
View view = getLayoutInflater().inflate( R.layout.line, null );
ImageView imageView = (ImageView) view.findViewById( R.id.imageView );
TextView textView = (TextView) view.findViewById( R.id.textView );
viewHolder = new ViewHolder();
viewHolder.imageView = imageView;
viewHolder.textView = textView;
view.setTag( viewHolder );
viewHolder.imageView.setImageResource( R.drawable.ic_launcher );
viewHolder.textView.setText( arr[ position ] + "");
return view;
} else {
viewHolder = (ViewHolder) convertView.getTag();
viewHolder.imageView.setImageResource( R.drawable.ic_launcher );
viewHolder.textView.setText( arr[ position ] + "");
return convertView;
}
}

因为convertView只是指向一块内存区域，它保存着已显示过的View。只有ListView没超出屏幕时，convertView才为空。如果超出了，convertView就有东西了。

附：ViewHolder如下：

class ViewHolder {
TextView textView;
ImageView imageView;
}